phase diagram and dielectric properties of...

1

SUPPORTING INFORMATION

for

Phase Diagram and Dielectric Properties of

MA1-xFAxPbI3

Ashutosh Mohanty, Diptikanta Swain, Sharada Govinda, Tayur N. Guru Row and D. D.

Sarma*

Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru - 560012,

India

Corresponding Author (E-mail: [email protected])

Experimental Methods:

(i) Synthesis of Samples: MA1-xFAxPbI3 samples (for x = 0.05, 0.075, 0.10, 0.125, 0.15,

0.175, 0.2, 0.3 and 0.4) were synthesized from the precursor solution containing methyl

ammonium iodide (MAI), formamidinium iodide (FAI) and lead iodide (PbI2) in appropriate

proportions.

Synthesis of precursors: MAI was prepared from methyl amine and concentrated HI (57% in

water) taken in an equimolar quantity, which were then mixed and stirred for 2 hour at 0 °C.

The resultant mixture was distilled at 50-60 °C for 4-5 hours to remove the solvent and as a

result white precipitate was obtained. The precipitated solid (i.e. MAI) was repeatedly

washed with diethyl ether to remove excess HI present in the sample. The precipitate was

recrystallized in ethanol and this recrystallized MAI again was washed with diethyl ether.

After sufficient washing, the obtained clean white solid was dried under vacuum and stored

2

under inert atmosphere. It was used as it is; for further synthesis procedures. FAI was

prepared by following the above procedures by taking equimolar amount of formamidinium

acetate and concentrated HI (57% in water).

Single crystal and polycrystalline MA1-xFAxPbI3 samples: As obtained MAI, FAI and PbI2

were used as precursors for synthesizing series of MA1-xFAxPbI3 samples. MAI (1-x moles),

FAI (x moles) and PbI2 (1 moles) were stoichiometrically mixed in γ-Butyrolactone (GBL) to

make 1M solution. This mixture was heated at 60 °C with constant stirring for 30-40 min to

dissolve the precursors completely and thus a clear solution was obtained. This solution was

drop-casted on clean glass slides, which was already kept at 105 °C, heated for 20 min at this

temperature to evaporate all the solvent. The resulting black powders and few small crystals

obtained on glass slide were scrapped off, collected and stored separately in N2 atmosphere

for powder and single crystal XRD measurements respectively.

(ii) Temperature Dependent Powder and Single Crystal XRD Measurement: The powder X-

Ray Diffraction data were collected on phase pure samples at specific temperatures

(mentioned as cyan dot in the phase diagram) in Bruker D8 Advance X-Ray diffractometer

by using Cu Kα radiation (λ = 1.5406 Å) equipped with a PheniX Oxford closed cycle helium

cryostat. The PheniX is uniquely designed for powder diffraction data collection at very low

temperatures in reflection geometry with good temperature stability of 0.1 K. The

measurement was carried out in cooling cycle starting from 295 K down till 15 K. Profile

fitting of PXRD patterns at selected temperatures are carried out by using JANA2006.1 The single

crystal XRD data at different temperatures were collected on selected compositions in Oxford

Xcalibur diffractometer with Mo Kα radiation (λ = 0.71073 Å) to determine the cation

orientations and the space group of the system in respective regions found in the phase

diagram namely cubic, tetragonal, large-cell cubic and orthorhombic phases. The single

crystals were smeared with paraton-N oil to avoid exposure to moisture and then mounted on

3

a Hampton cryo-loop. The crystal was maintained at the desired temperature under a nitrogen

gas stream from the Oxford cryo-systems open-flow cryostat (COBRA) using liquid nitrogen.

Data collection, data reduction and numerical absorption corrections were performed by using

CrysAlisPro2 software suite. The structure solution and refinement were accomplished by using

SHELXS and SHELXL 3,4 included in the WinGX suite5. Profile refinement for the XRD pattern

at different crystallographic phases for all compositions have been shown in Figures S1 - S9

and respective refinement parameters are included in the Tables S1 - S9. All temperature

dependent XRD pattern collected for various compositions are represented in Figures S10 –

S18.

(ii) Dielectric Measurement: The samples were ground and approximately 85 mg powder was

pressed under hydrostatic pressure of around 1.5 N/mm2 to make pellets of 6 mm diameter.

The pellets were annealed at 50-60 °C for 2 hour to get better connectivity in the grains.

Silver paste was used to make electrode on both the faces of the pellet and the temperature

dependent dielectric measurements were carried out in a closed cycle helium cryostat (Cryo

Industries Inc.) using a Keysight E4990A Impedance Analyzer. The measurements were

performed in the frequency range of 1 kHz - 1 MHz by cooling the sample from room

temperature down to 12 K, in steps of 0.5 K with a scan rate of 0.5 K/min. The measurements

were also done in the heating cycle to check the reproducibility. The results from both the

cycles overlapped except some hysteresis of few K found at phase transition temperatures

indicative of the transition being first order in nature.

4

Figure S1. Powder XRD pattern and profile refinement for MA0.95FA0.05PbI3 at (a) 295 K, (b)

130 K and (c) 15 K. Details of refinement parameters are given in Table S1.

Table S1. Fitting parameters for FA0.05MA0.95PbI3 sample obtained from profile refinement

Composition MA0.95FA0.05PbI3

Temperature 295K

(Single phase)

130K

(Multi-phase)

15K

(Single Phase)

Crystal

system

Tetragonal Tetragonal

(Phase-1)

Orthorhombic

(Phase-2)

Orthorhombic

Space group I4/mcm I4/mcm Pnma Pnma

a(Å) 8.86083(16) 8.79161(39) 8.86274(22) 8.84186(24)

b(Å) 8.86083(16) 8.79161(39) 12.61363(27) 12.5970(28)

c(Å) 12.63719(22) 12.66423(88) 8.59362(23) 8.56419(24)

V(Å3) 992.20(18) 978.85(81) 960.69(11) 953.89(53)

2 1.56 1.35 1.76

RP 6.73 5.83 7.44

5

Figure S2. Powder XRD pattern and profile refinement for MA0.925FA0.075PbI3 at (a) 295 K,

(b) 120 K and (c) 15 K. Details of refinement parameters are given in Table S2.

Table S2. Fitting parameters for MA0.925FA0.075PbI3 sample obtained from profile refinement


Temperature 295K

(Single phase)

120K

(Multi-phase)

15K

(Single Phase)

Crystal

system

Tetragonal Tetragonal

(Phase-1)

Orthorhombic

(Phase-2)

Orthorhombic

Space group I4/mcm I4/mcm Pnma Pnma

a(Å) 8.87250(16) 8.78498(25) 8.86450(24) 8.83494(73)

b(Å) 8.87250(16) 8.78498(25) 12.61481(28) 12.59348(10)

c(Å) 12.64340(28) 12.67204(66) 8.596653(23) 8.56284(71)

V(Å3) 995.30(35) 977.98(58) 961.31(79) 952.72(23)

2 1.39 1.46 1.53

RP 6.88 6.46 6.74

6


150 K, (c) 130 K, (d) 110 K and (e) 15 K. Details of refinement parameters are given in Table

S3.

7



Temperature 295K

(Single

phase)

150K

(Multi-phase)

130K

(Single phase)

110K

(Multi-phase)

15K

(Single phase)

Crystal

system

Cubic Tetragonal

(Phase-1)

Cubic

(Phase-2)

Cubic

Cubic

(Phase-1)

Orthorhombic

(Phase-2)

Orthorhombic

Space group I4/mcm I4/mcm Im-3 Im-3 Im-3 Pnma Pnma

a(Å) 8.88533(17) 8.79708(18) 12.47523(48) 12.43300(23) 12.42632(29) 8.596097(25) 8.84299(28)

b(Å) 8.88533(17) 8.79708(18) 12.47523(48) 12.43300(23) 12.42632(29) 12.61242(27) 12.59522(31)

c(Å) 12.63297(28

)

12.67490(33) 12.47523(48) 12.43300(23) 12.42632(29) 8.863799(22) 8.572983(27)

V(Å3) 997.362(36) 980.90(40) 1941.54(71) 1921.89(36) 1918.79(44) 960.99(32) 954.85(59)

2 1.36 1.77 1.83 1.32 1.52

RP 6.37 8.36 8.73 6.35 7.47

8


250 K, (c) 150 K, (d) 120 K, (e) 100 K and (f) 15 K. Details of refinement parameters are

given in Table S4.

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Table S4. Fitting parameters for MA0.875FA0.125PbI3 sample obtained from profile refinement Composition MA0.875FA0.125PbI3

Temperature 310K

(Single

phase)

250K

(Single

phase)

150K

(Multi-phase)

120K

(Single phase)

100K

(Multi-phase)

15K

(Single phase)

Crystal

system

Cubic Tetragonal Tetragonal

(Phase-1)

Cubic

(Phase-2)

Cubic

Cubic

(Phase-1)

Orthorhombic

(Phase-2)

Orthorhombic

Space group Pm-3m I4/mcm I4/mcm Im-3 Im-3 Im-3 Pnma Pnma

a(Å) 6.30304(12) 8.85399(16) 8.80089(32) 12.44843(16) 12.43350(70) 12.42186(25) 8.86514(30) 8.85655(48)

b(Å) 6.30304(12) 8.85399(16) 8.80089(32) 12.44843(16) 12.43350(70) 12.42186(25) 12.61891(34) 12.61487(60)

c(Å) 6.30304(12) 12.66350(26) 12.66076(48) 12.44843(16) 12.43350(70) 12.42186(25) 8.600199(31) 8.59131(49)

V(Å3) 250.41(51) 992.73(34) 980.6465(53) 1929.05(91) 1922.12(10) 1916.73(39) 962.09(27) 959.86(14)

2 1.77 1.34 1.68 1.81 1.78 1.96

RP 6.58 6.67 6.49 6.82 6.71 7.30

10


220 K, (c) 170 K, (d) 120 K and (e) 15 K. Details of refinement parameters are given in Table

S5.

11



Temperature 295K

(Single

phase)

220K

(Single

phase)

170K

(Multi-phase)

120K

(Single phase)

15K

(Multi-phase)

Crystal system Cubic Tetragonal Tetragonal

(Phase-1)

Cubic

(Phase-2)

Cubic Cubic

(Phase-2)

Orthorhombic

(Phase-1)

Space group Pm-3m I4/mcm I4/mcm Im-3 Im-3 Im-3 Pnma

a(Å) 6.29922(9) 8.84675(19) 8.81457(35) 12.46748(22) 12.44343(22) 12.40334(31) 8.58265(31)

b(Å) 6.29922(9) 8.84675(19) 8.81457(35) 12.46748(22) 12.44343(22) 12.40334(31) 12.59596(36)

c(Å) 6.29922(9) 12.66227(31) 12.66381(49) 12.46748(22) 12.44343(22) 12.40334(31) 8.84513(28)

V(Å3) 249.95(37) 991.01(40) 983.93(54) 1937.92(93) 1926.728(35) 1908.17(10) 956.22(64)

2 1.49 1.83 1.84 1.72 1.58

RP 6.39 7.44 7.54 7.08 6.47

12

Figure S6. Powder XRD pattern and profile refinement for MA0.825FA0.175PbI3 at (a) 295 K,

(b) 230 K, (c) 190 K and (d) 15 K. Details of refinement parameters are given in Table S6.



Temperature 295K

(Single phase)

230K

(Single phase)

190K

(Multi-phase)

15K

(Single phase)

Crystal

system

Cubic Tetragonal Tetragonal

(Phase-1)

Cubic

(Phase-2)

Cubic

Space group Pm-3m I4/mcm I4/mcm Im-3 Im-3

a(Å) 6.30213(86) 8.84934(16) 8.82535(15) 12.50214(39) 12.39421(18)

b(Å) 6.30213(86) 8.84934(16) 8.82535(15) 12.50214(39) 12.39421(18)

c(Å) 6.30213(86) 12.66186(26) 12.67016(27) 12.50214(39) 12.39421(18)

V(Å3) 250.30(34) 991.56(34) 986.84(33) 1954.13(58) 1903.96(28)

2 1.64 1.32 1.24 1.37

RP 6.85 6.88 6.31 6.97

13


220 K and (c) 15 K. Details of refinement parameters are given in Table S7.

14



Temperature 295K

(Single phase)

220K

(Multi-phase)

15K

(Single phase)

Crystal

system

Cubic Cubic

(Phase-1)

Tetragonal

(Phase-2)

Cubic

Space group Pm-3m Im-3 I4/mcm Im-3

a(Å) 6.30460(32) 12.53501(23) 8.85236(40) 12.39585(36)

b(Å) 6.30460(32) 12.53501(23) 8.85236(40) 12.39585(36)

c(Å) 6.30460(32) 12.53501(23) 12.64178(57) 12.39585(36)

V(Å3) 250.59(13) 1969.58(36) 990.66(25) 1904.711(55)

2 1.23 1.27 1.66

RP 6.31 6.54 8.18

Figure S8. Powder XRD pattern and profile refinement for MA0.7FA0.3PbI3 at (a) 295 K and

(b) 15 K. Details of refinement parameters are given in Table S8.

15



Temperature 295K

(Single phase)

15K

(Single phase)

Crystal

system

Cubic Cubic

Space group Pm-3m Im-3

a(Å) 6.31072(87) 12.44621(25)

b(Å) 6.31072(87) 12.44621(25)

c(Å) 6.31072(87) 12.44621(25)

V(Å3) 251.32(35) 1928.02(39)

2 1.37 1.83

RP 6.14 7.75

Figure S9. Powder XRD pattern and profile refinement for MA0.6FA0.4PbI3 at (a) 295 K and

(b) 15 K. Details of refinement parameters are given in Table S9.

16



Temperature 295K

(Single phase)

15K

(Single phase)

Crystal

system

Cubic Cubic

Space group Pm-3m Im-3

a(Å) 6.31543(11) 12.44621(25)

V(Å3) 251.88(44) 1928.02(39)

2 1.94 2.11

RP 7.49 8.35

Figure S10. The plot shows powder XRD pattern for MA0.95FA0.05PbI3 at different

temperatures.

10 20 30 40 50 60 70 80

1400

2800

4200

5600

7000

50

100

150

200

250

2 (degree)

Tem

per

ature

(K

)

Inte

nsit

y (

a.u

.)

17


temperatures.


temperatures.

10 20 30 40 50 60 70 80

900

1800

2700

3600

50

100

150

200

250

Inte

nsit

y (

a.u

.)

2 (degree)

Tem

per

ature

(K

)

10 20 30 40 50 60 70 80

1600

3200

4800

6400

8000

50

100

150

200

250

Inte

nsit

y (

a.u

.)

2(degree)

Tem

pera

ture

(K)

18


temperatures.


temperatures.

10 20 30 40 50 60 70 80

1400

2800

4200

5600

7000

50

100

150

200

250

300

Inte

nsit

y (

a.u

.)

2 (degree)

Tem

per

ature

(K

)

10 20 30 40 50 60 70 80

1400

2800

4200

5600

7000

50

100

150

200

250

Inte

nsit

y (

a.u

.)

2 (degree)

Tem

per

ature

(K

)

19


temperatures.


temperatures.

10 20 30 40 50 60 70 80

0

1300

2600

3900

5200

50

100

150

200

250

Inte

nsit

y (

a.u

.)

2 (degree)

Tem

per

ature

(K

)

10 20 30 40 50 60 70 80

1500

3000

4500

6000

7500

280

240

200

160

120

80

40

2(degree)

Inte

nsit

y (

a.u

.)

Tem

per

ature

(K

)

20


temperatures.


temperatures.

10 20 30 40 50 60 70 80

1600

3200

4800

6400

8000

50

100

150

200

250

Inte

nsit

y (

a.u

.)

2 (degree)

Tem

pera

ture

(K)

10 20 30 40 50 60 70 80

1600

3200

4800

6400

8000

50

100

150

200

250

Inte

nsit

y (

a.u

.)

2 (degree)

Tem

per

ature

(K

)

21

Figure S19. The plot shows the function F(R) as a function of the photon energy,

representing the absorption behaviour, obtained using the Kubelka-Munk formula from

experimentally obtained diffuse reflectance spectra of MA1-xFAxPbI3 solid solution for

different x values at RT.

Figure S20. The plot shows the room temperature photoluminescence (PL) spectra for MA1-

xFAxPbI3 solid solution for different x values. The PL was recorded with a 470 nm excitation

source.

1.3 1.4 1.5 1.6 1.7 1.8

0

1

2

3

4

F(R

)

Energy (eV)

x = 0.00

x = 0.05

x = 0.075

x = 0.10

x = 0.125

x = 0.15

x = 0.175

x = 0.20

x = 0.30

x = 0.40

1.50 1.55 1.60 1.65

0.0

0.2

0.4

0.6

0.8

1.0

PL

Inte

nsity (

a.u

.)

Energy (eV)

x = 0.00

x = 0.05

x = 0.075

x = 0.10

x = 0.125

x = 0.15

x = 0.175

x = 0.20

x = 0.30

x = 0.40

22

REFERENCES:

(1) Petricek, V.; Dusek, M.; Palatinus, L. Crystallographic computing system JANA2006:

general features. Zeitschrift für Kristallographie-Crystalline Materials 2014, 229(5), 345-

352.

(2) Rigaku Oxford Diffraction CrysAlisPro Software System, version 1.171.38.46; Rigaku

Corporation: Oxford, UK, 2018.

(3) Sheldrick, G. M. SHELXS-2013, SHELXL-2013; Program for Crystal Structure

Solution and Refinement. University of Göttingen: Germany, 2013.

(4) Sheldrick, G. M. Crystal structure refinement with SHELX Acta Cryst. 2015, C71, 3-8

(5) Farrugia, L. WinGX suite for small-molecule single-crystal crystallography. J. Appl.

Crystallogr. 1999, 32, 837–838.

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